Method for manufacturing gel

ABSTRACT

An improved method for manufacturing a foam inhibitor for soluble oils is described. The foam inhibitor is a gel of a mineral oil of lubricating viscosity, about 2 to 10 weight percent of a petroleum microcrystalline wax and about 1 to 10 weight percent of a polymer of ethylene having a molecular weight of about 1,000 to 12,000. A mixture of these components is heated at a temperature sufficient to provide a solution and the heated solution is shock cooled by adding particles of solid carbon dioxide in an amount sufficient to cool the mixture to a temperature below about 120* F. in a time sufficient to yield a gel having low particle size and a high degree of particle distribution of the ethylene polymer and the wax.

United States Patent Matson et al. Jan. 25, 1972 METHOD FORMANUFACTURING GEL OTHER UBLICATIONS [72] Inventors: How. M'mn, Markham,Kirk-Othmer Encyclopedia of Chemical Technol." Vol. 4

Fritz, Atlanta, (2nd Ed.) 1964) pages 366- 367.

[73] Assignees Atlantic Richfleld Company, New York, p m E. wymanAssistant Examiner-W. Cannon '22] Filed July 199 AttorneyMcLean, Mortonand Boustead [2!] Appl. No.: 041,122 [57] ABSTRACT An improved methodfor manufacturing a foam inhibitor for [52] U.S.Cl ..2S2/59, 252/16,252/495, soluble oils is described. The foam inhibitor is a gel of a252/316, 52/358 mineral oil of lubricating viscosity, about 2 to l0weight per- [51] Int. Cl. ..Cl0m l/l cent of in petroleummicrocrystalline wax and about I to 10 [58] Field oISearch ..2S2/l6, 59,49.5, 308, 3l6. weight percent of a polymer of ethylene having amolecular 2 7; 2 7 weight of about 1,000 to [2,000. A mixture of thesecomponents is heated at a temperature sufficient to provide a solu- 56]References Cited tion and the heated solution is shock cooled by addingparlicles of solid carbon dioxide in an amount sufficient to cool theUNITED STATES PATENTS mixture to a temperature below about 120 F. in atime surfi- 2 m4 065 10/:952 Wanderer et 3|. ..2os/35 Ciel Yield i=havinl 10W P size and a s a 2'77556l |2/|956 Frohmader e aluu ""252/59 Xof particle distribution of the ethylene polymer and the wax. 2,972,5782/1961 Roehler ..252/49.5 X 7 M N D 3,078,237 2/1963 Creech et al.....2s2 352 C METHOD FOR MANUFACTURING GEL This invention relates to animproved method of forming a foam inhibitor. in particular, thisinvention relates to an improved method for forming a gel of a mineraloil of lubricating viscosity, about 2 to 10 weight percent of apetroleum microcrystalline wax and about 1 to 10 weight percent of apolymer of ethylene having a molecular weight of about 1,000 to l2,000wherein a means for cooling is provided so that the temperature drop atcertain steps does not fall below a minimum value.

Metalworking oils, such as soluble or emulsifiable cutting oils, arefrequently employed under conditions which include extreme agitation andhigh pressure application. The conditions cooperate to effectlubrication and cooling but disadvantageously produce foam. Foam caninterfere with visual control of the operation being effected, caninsulate the piece being worked from the cooling action which thelubricant otherwise exerts and can escape the immediate work area andresult in unsatisfactory operating conditions. Accordingly, it isundesirable that foam, especially stable foam, be produced duringmetalworking operations.

As disclosed in U.S. Pat. No. 2,972,578, the addition of the gels withwhich the present invention is concerned to a soluble oil results in acomposition characterized by the ability to resist fonnation of and todestroy foam occurring during use. As described in the mentioned patentthe gels of the present invention have been prepared by adding thepolymer and wax to the material which comprises the liquid organicmedium together, or one at a time, treating in a manner that effectssolution and then rapidly cooling or chilling the mixture to obtain thegel. Rapid chilling has been used in the production of gels of the mostsatisfactory characteristics. This necessity of rapid chilling hasnaturally presented certain difficulties with respect to adequatecooling. For instance, it has been found, that in attempting to producea satisfactory gel in warm climates such as during summer months of peakambient temperature, i.e., at least about 80 F., employment of ordinarycooling media such as ambient temperature water or air by indirect heatexchange fails to effect the required rapid cooling so that the mostadvantageous gel formation is not obtained. Consequently, a lesseffective foam suppressor is produced unless inconvenient and moreexpensive indirect cooling methods are relied upon such as refrigeratingmeans, ice cooled water, ice packs, etc., to overcome this difficulty.The problem has become severe when it is desired to produce largequantities of the gel throughout the year without provision of specialcooling means or when it is desired to produce the gel in field serviceoperations where special cooling means are not readily available.

In U.S. Pat. No. 3,078,237, there is disclosed a method of producing thegels of the present invention without necessarily resorting to rapidcooling. In accordance with that method, the ethylene polymer and waxare added, together or one at a time, to the organic liquid whichcomprises the organic medium, and the mixture is at or is heated to atemperature sufficient to effect solution of the polymer and wax. Themixture is then cooled to a temperature below the cloud point of themixture, preferably at least about 5 F. below the cloud point, andreheated to a temperature within the range of immediately above thecloud point of the mixture, e.g., at least about 1 F. above, to about 20F. above the cloud point, preferably up to about F. above the cloudpoint and not above about [70 F. to effect dissolution. The mixture isthen permitted to cool to below about I F., usually to room temperature.Although this patent discloses that the cooling from above the cloudpoint to below about 120 F. need not be performed using external coolingmeans, it has been found that this method is also temperature-sensitive,particularly during prolonged periods of hot weather, i.e., when ambienttemperature is about 80 F. or higher. The cooling problem occurs duringthe cooling period from above the cloud point to below about I20 F. Thiscooling period apparently affects the particle size or particledistribution in the total mix. it has been found that when the coolingperiod requires 6 or 8 hours, the mixture has little or no foaminhibitor activity. Best results can be obtained when the cooling periodrequires about 2 hours or less.

This invention produces suitable foam inhibitors of the type describedabove by providing in the total mix while in the molten state, particlesof solid carbon dioxide. The carbon dioxide provides shock-chilling ofthe mixture, thereby reducing the temperature of the mix in a rapidmanner to give the particle size and particle distribution required forfoam inhibition. The process is especially effective when the moltenmixture is cooled by indirect heat exchange with a fluid having atemperature of at least about F. due to ambient temperatures being ofthis magnitude. The use of solid carbon dioxide as a cooling means isapplicable to the methods disclosed and claimed in U.S. Pat. Nos.2,972,578 and 3,078,237, and in spite of the fact that solid carbondioxide is added to the gelforrning mixture the structure of theresulting gel is satisfactory for foam-inhibiting purposes. Thus evenwith direct heat exchange between the carbon dioxide and the moltenmixture the desired gel structure was not adversely affected.

The invention thus provides for a method of producing a gel as hereinbefore described by heating the mixture of said oil of lubricatingviscosity, ethylene polymer and microcrystalline wax at a temperaturesufficient to provide solution and shock cooling the mixture by addingparticles of solid carbon dioxide to the mixture in an amount sufficientto cool the mixture to a temperature below about 120 F. in a timesufficient to yield a gel of low-particle size and a high degree ofparticle distribution of the ethylene polymer and the wax. The amount ofsolid carbon dioxide added preferably is sufficient to cool the mixtureto below about l20 F. in about 2 or 3 hours or less. The solution can bealso first cooled below the cloud point of the mixture, reheated to atemperature within the range of immediately above the cloud point of themixture to about 20 F. above the cloud point, and then finally cooled toa temperature of below about I20 F. by providing in the reheated mixturethe solid carbon dioxide as described above.

The composition of the invention can be employed in lubricants inMetalworking operations, especially soluble cutting oils. Solublecutting oils are well-known commercial products generally comprising arefined lubricating oil base, a soap or other emulsifying agent and acommon solvent and/or coupling agent, the materials being present inamounts such that a stable emulsion can be formed by the composition andabout 1 to 50 parts of water. Typical soluble oils comprise alubricating oil base, about l0 to 25 weight percent of an emulsifiersuch as a sulfonate, naphthenate or oleate, about 3 to 7 weight percentof a secondary emulsifier such as sodium rosinate or analogous metalsalt, and about 0.5 to l weight percent of an oxygen containing,hydrocarbon coupling agent such as ethyl or butyl Cellosolve (glycolethyl ether or glycol butyl ether) or diethylene glycol. Additives suchas bactericides and extreme pressure agents and the like also arefrequently included to advantage.

For the best service it has been found that compounding of the solubleoil and the gel should be accomplished under certain conditions. Forexample, it has been found that the prepared additive should not beincorporated in the soluble oil when the temperature of the soluble oilis greater than about 150' F. Thus, the additive can be dispersed in thesoluble oil at a temperature of about F. while mildly agitating, andtemperatures of about 70" F. to 125 F. have been found to beparticularly satisfactory. The most advantageous temperature to beemployed is determined primarily by the quantity of additive used. Forexample, with about 3 percent additive a temperature of about l00 F. ismost desirable while with 5 percent, temperatures of about to F. appearto be optimum. The foam inhibited soluble oils can also be produced bydispersing the additive components directly into the soluble oil attemperatures of gel formation as mentioned above rather than performingthe additive composition and then adding it as such. In this instancealso the use of high temperatures, that is above about l50 F. after theadditive has formed, should be avoided. The antifoam additive isemployed in soluble oils in an amount effective to inhibit formation ofand destroy foam occurring in use. Generally about 0.05 to 20 weightpercent of the additive, and particularly 3 to 7 weight percent, isemployed, based on the resulting soluble oil-additive composition anddepending upon the soluble oil used and the use contemplated.

The polymeric materials employed in the present invention are knownarticles of commerce. They are polymers of ethylene having molecularweights of about 1,000 to 12,000, preferably about 1,500 to 2,500. Thepolymers generally are used in amounts of about 1 to weight percent ofthe gel composition, and preferably about 1 to 4 weight percent. Inaddition to the usual ethylene polymers, terminal hydroxylcontainingpolymers of ethylene conforming to the preceding physical propertiesalso can be used. The preferred polymers are terminalhydroxyl-containing polymers of ethylene having a molecular weight ofabout 2,000 to 2,200. In general, terminal hydroxyl-containing polymersare prepared by polymerizing ethylene at the usual conditions oftemperature and pressure, that is at pressures from about 800 to 3,000atmospheres and temperatures from about 390 to 750 F., with or without afree radical forming catalyst such as hydrogen peroxide and in thepresence of hydroxyl-containing chain stopper such as isopropanol.Commercially available examples of satisfactory hydroxyl-containingpolymers are Alcowax No. 6 and No. 7, available from Allied ChemicalCompany. Conditions for the preparation of these materials are wellknown as is evidenced by US. Pat. Nos. 2,504,400 and 2,683,141. Byterminal hydroxyl containing we intend to indicate that a hydroxylradical is on one of the end five or 10 carbon atoms rather than beingcentrally located in the molecule. It is believed that the hydroxylradical generally oc curs on one of the end three carbon atoms.

The microcrystalline wax component which can be used in the presentinvention is an article of commerce produced from petroleum oils.Microcrystalline waxes can be obtained from Pennsylvania or Midcontinentcrude oils and are generally characterized by a large percentage ofnonnormal paraffins and advantageously melt in the range from about 120to 200 F. (PMP). Typical properties include a petrolatum melting point(PMP) from about 165 to 175 F., a viscosity at 210 F. of about 65 to 80Saybolt Universal Seconds and a penetration at 77 F. of about 11 to 14.The wax is usually about 2 to 10 weight percent of the gel composition,preferably about 3 to 8 percent.

The major portion and preferably the substantial balance of the novelgel compositions of this invention comprises a liquid organic medium,for example a suitable oil. Suitable oils are those of lubricating oilviscosity and preferably those having a viscosity at 100 F. ranging fromabout 50 to 150 S.U.S. Oils which are too light may result in bleedingin the resulting gels and those which are too heavy frequently renderthe gels difficult to disperse in soluble oils. The oils preferably aremineral base and can be obtained from any known crude. Particularlysatisfactory oils include naphthenic base lubricating oil fractionshaving a viscosity of about 100 S.U.S. at 100 F.

Thus typical compositions include a gel composed, for example, of aliquid organic medium, about 2 to 10 weight percent of the wax and about1 to 10 weight percent of ethylene polymer. A typical specificcomposition is a gel containing a naphthenic base lubricating oilfraction having a viscosity of 100 S.U.S. at 100 F., 5 weight percent ofa paraffin base microcrystalline wax having a PM? melting point of about165 F. and 2 weight percent of a polymer of ethylene having a molecularweight of 1,800. In the soluble oil compositions, a typical specificcomposition is 5 weight percent of the above specific gel dispersed in asoluble oil consisting of a Midcontinent base lubricating oil having aviscosity at 100 F. of 125 S.U.S., 15 weight percent of sodium mahoganysulfonate, 5 weight percent of sodium rosinate and 2 weight percent ofdiethylene glycol. All percentages are by weight percent based on theresulting compositions, unless otherwise specified. While a gel is thespecified and preferred physical state of use,

the foam inhibiting composition can be used as a liquid provided it hasfirst been a gel.

In addition to the components of the gel compositions described, and ofthe soluble oils where employed, the compositions can also contain otheradditives commonly employed in the art in the usual amounts so long asthe foamdepressing and foam-breaking properties are not undulydeleteriously affected. Such additives include antioxidants, wettingagents, extreme pressure agents, antistaining agents and so on.

The carbon dioxide particles are added to the solution in an amountsutficient to cool the solution to a temperature below about 120 F. in atime sufficient to yield a gel having low-particle size and a highdegree of particle distribution of the ethylene polymer and wax. Theamount of carbon dioxide particles added is generally sufficient to coolthe mixture to a temperature below about 120 F. in about 2 hours orless. This amount may vary depending on the temperature of the solution,ambient temperature, etc., but can often be from about 0.1 to 10 weightpercent of the mixture, preferably about 0.5 to 5 weight percent. Thecarbon dioxide particles are of a size sufficient to provide the coolingarea to give the desired cooling rate and can often range from about 1inch to about 1 foot, preferably from about 2 to 8 inches, in the widesttransverse dimension. The particles can be of any desired shape and areoften irregularly shaped particles produced from commercially availableslabs of carbon dioxide.

The invention will be described further in connection with the followingexamples. It should be understood that the details disclosed are notintended as limiting the invention.

EXAMPLE I A typical commercial procedure for making the foam inhibitorbased on US. Pat. No. 2,972,578 can be by adding 800 pounds of anaphthenic lube oil having a viscosity of 100 S.U.S. at 100 F., intoajacketed kettle and heating to 220 F. Thirty pounds of a terminalhydroxyl-containing polymer of ethylene having a molecular weight of2,100 are added and stirred 15 minutes or until dissolved. The mixtureis cooled rapidly by indirect heat exchange to 170 F., and then 75pounds melted paraffin base microcrystalline wax having an AMP meltingpoint of 128 F. are. added. Cooling is continued while adding 595 poundsof the lube oil. After all oil has been added, stirring is stoppedexcept for about 2 minutes out of each hour, and cooling is continueduntil temperature reaches F.

Commercial experience has shown that during winter months, when coolingwater temperature can be as low as about 40 F., and the above coolingcan be effected within about 3 to 4 hours, a satisfactory product isproduced. As this time is exceeded, due to use of higher temperaturecooling water as is common during warm weather months, the productbecomes less effective, presumably because of a change in particle sizedue to the slower cooling.

EXAMPLE I] A typical manufacture using the procedure of US. Pat. No.3,078,237 can be by adding 1,500 pounds of the lube oil of example 1into a kettle, together with pounds of the polyethylene of example I.This mixture is heated to 220 F. and mixed until blended. Two hundredfifty pounds of the wax of example I are added at 220 F. and mixed untilblended. Three thousand fifty pounds of the lube oil are then added, andthe total mixture cooled by indirect heat exchange to F. The mixture isthen reheated to -175 F. to give a homogenous solution. and then cooledto 120 F.

Although this modification has enabled the manufacture of a moreconsistently active foam inhibitor material, problems have also beenencountered during prolonged hot weather periods such as to raisecooling water temperatures to about 80 F. or higher. The problem occursduring the cooling of the product mixture from about l65-175 F., toabout 120 F. It

is this cooling period that apparently affects the particle size orpattern distribution in the total mix. In general, it has been foundthat when cooling water temperature exceeds about 80 F., often requiringmore than about 6 to 8 hours to cool to 120 F., the mixture has littleor no foam inhibitor activity. Best results have been obtained when thiscooling period requires about 2 hours or less.

EXAMPLE 111 One thousand five hundred pounds of the lube oil of examplel and 100 pounds of the polyethylene of example 1 were heated withmixing to 220 F. until blended. Two hundred and fifty pounds of themicrocrystalline wax of example I were then added at 220 F., and mixeduntil blended with no further heat applied. Three thousand one hundredand fifty pounds of the lube oil were then added and the total mixturecooled to 140 F. by indirect heat exchange with water at above 80 F. Themixture was then reheated to 165 F. in the manner taught by U.S. Pat.No. 3,078,237 to give a homogeneous solution. At this point, thereaction mixture was subjected to shock cooling by adding 80 pounds offist size pieces of solid carbon dioxide. By this means, cooling tobelow 120 F. was effected in less than 1 hour.

The 1 hour cooling time from 165 F. to below 120 F. by this improvedprocess compares with a range from about 12 hours down to more thanabout 2 hours as the least cooling times possible by the processes ofthe above-mentioned prior art.

EXAMPLE IV The effectiveness of a soluble oil foam inhibitor can beevaluated by means of the following foam test:

One gram of foam inhibitor is blended with 99 grams of heat soluble oilby stirring at room temperature and this blend is used to make a 1:20dilution of finished soluble oil in distilled water. A 100 ml. portionof the water diluted blend is shaken vigorously for 30 seconds, andobserved for foam level after 5 minutes standing. It has been found thatthose mixtures which show a maximum foam level of 1 ml. after 5 minuteswill give satisfactory nonfoaming performance in field service.

The following foam test data compares the effectiveness of products madeby the preceding examples:

Typical foam test, ml. foam,

Winter Summer 5 mln.

Typical cooling time, hrs.

Anti-foam Manufacturing acceptance procedure The above data shows themore rapid cooling that can be obtained with the instant process and themore effective antifoam properties of the resulting manufacturedproduct.

The improved manufacturing process of this invention has an obvioussaving in processing time due to the more rapid cooling rate in thefinal stages. More important however, this improved process provides afoam inhibitor under conditions which up to this time prohibitedmanufacture and, in addition, provides a material having superiorantifoam properties.

It is claimed:

1. A method for producing a gel consisting essentially of a major amountofa mineral oil of lubricating viscosity, about 1 to ID weight percentof an ethylene polymer having a molecular weight of about 1,000 to12,000 and about 2 to 10 weight percent of a petroleum microcrystallinewax, which comprises heating the mixture of said oil of lubricatingviscosity, ethylene polymer and microcrystalline wax, at a temperaturesufficient to provide solution and shock cooling the solution byproviding therein particles of solid carbon dioxide in an amountsufficient to cool the mixture to a temperature below about 120 F. in atime of about 3 hours or less sufficient to yield a gel havinglow-particle size and a high degree of particle distribution of theethylene polymer and wax.

2. The method of claim 1 wherein the carbon dioxide is added in anamount sufficient to cool the mixture to a temperature of below about120 F. in about 2 hours or less.

The method of claim 1 wherein the solution is cooled below the cloudpoint of the mixture and reheated to a temperature within the range ofimmediately above the cloud point of the mixture to about 20 F. abovethe cloud point prior to shock cooling.

4. The method of claim 3 wherein the carbon dioxide is added in anamount sufficient to cool the mixture to a temperature of below about120 F. in 2 hours or less.

5. The method of claim 4 wherein the carbon dioxide is added in anamount of from about 0.1 to 10 weight percent of the solution.

6. The method of claim 5 wherein the carbon dioxide is added in anamount of from about 0.5 to 5 weight percent of the solution.

7. The method of claim 1 wherein the ambient temperature is at least F.

2. The method of claim 1 wherein the carbon dioxide is added in anamount sufficient to cool the mixture to a temperature of below about120* F. in about 2 hours or less.
 3. The method of claim 1 wherein thesolution is cooled below the cloud point of the mixture and reheated toa temperature within the range of immediately above the cloud point ofthe mixture to about 20* F. above the cloud point prior to shockcooling.
 4. The method of claim 3 wherein the carbon dioxide is added inan amount sufficient to cool the mixture to a temperature of below about120* F. in 2 hours or less.
 5. The method of claim 4 wherein the carbondioxide is added in an amount of from about 0.1 to 10 weight percent ofthe solution.
 6. The method of claim 5 wherein the carbon dioxide isadded in an amount of from about 0.5 to 5 weight percent of thesolution.
 7. The method of claim 1 wherein the ambient temperature is atleast 80* F.